Bevel-gear cutter



(ModeL) I 8 Sheets-Sheet 1. H. BILGRAM.

. BEVEL GEAR CUTTER. No. 294,844. P44811484 Mar. 11, 1884.

54 44 ZZZVWAM/ (ModeL) H. BILGRAM,

BEVEL GEAR CUTTER.

Patented Mar. 11 1884.

3 Sheets-Sheet 2.

3 SheetsShe.et 3.

(ModeL) H; BILGRAM.

BEVEL GEAR GUTTER.

No; 294,844. Patented Mar. 11, 1884.

N. PETERS, Fhoivljlmgmpher. Waslmglon. I). c.

rnrcn STATES PATENT HUGO BILGRAM, OF PHILADELPHIA, PENNSYLVANIA.

'BEVEL-GEAR CUTTER.

SPECIFICATION forming part of Letters Iatent No. 294,844, dated March11, 1884.

Application filed December 6, 1882, (Model) To all whom it may concern.-

Be it known that I, Huco BILGRAM, of the city and county of Philadelphia, and the State of Pennsylvania, have invented a new and usefulImprovement in Machines for Cutting the Teeth of Bevel-\Vheels, of whichthe following is a specification.

For cutting the teeth of bevel-wheels two distinct principles have beenemployed heretofore-i. 0., first, a toolis used, either reciprocatin gor rotary or both,the outline of which has a curved shape, conformingwith the shape the teeth are desired to obtain. This tool is generallyfed in two directions through the spaces betweentheteeth to produce thewedgeshaped or convergent form which these spaces are required to have.However, as the curve of the teeth in bevel-wheels, when correctlyformed, changes constantly from one end of the tooth to the other,bevel-wheels produced in this way are not theoretically correct, and,although the cutter is usually shaped so as to make the correct form atabout the middle of the face of the wheel, the sides of the teeth needsome filing if a tolerably well gearing bevel-wheel is desired. Thesecond principle employed in cutting the teeth of bevel-wheels partiallyovercomes this defect. It consists in the use of a pointed reciprocatingtool, the motion of the cutting-point of which is invariably directedtoward the apex of the bevelwheel, and which is capable ofrcceivingalateral motion, swinging on that apex. Thislateral motion isguided and directed by aguide or templet made of a shape correspondingwith the desired form of the teeth of the bevel-whcel. A separatetemplet is necessary for every varying shape of teeth, and thecorrectness of the work depends upon the accuracy with which thistemplet is made and adjusted. In order to produce correct teeth by thismode, the cutting-point of thetool should be a mathematical point-2 e.,the sharp point of an angular tool; but, as such a tool would produce avery rough surfacc,the point of the tool cmployed'must be more or lessrounded at the expense of theaccuraey of the resulting work, andnotwithstanding this sacrifice the surface produced will be made up of aseries of shallow rounded grooves,

which are at right angles to the motion of the gearing-cogs and induce agrating noise when running.

In my invention I employ a principle sub stantially difi'cring fromeither of those indi cated above-i. 6., the principle of evolutionandthus produce a theoretically correct tooth without the aid of anytemplet.

It is known that any number of gear-wheels which do correctly gear witha rack having teeth of the shape of a truncated wedge will alsocorrectly gear with one another, and by employing a reciprocating toolof the shape of such atooth, and rolling under it a gear-wheel on itspitchline, the reciprocating tool will cut the teeth to such a shapethat they will correctly gear with any other, wheel of the same pitch,the teeth of which are cut in the same manner and with the same tool, Inexplanation of this theory, I show in Fig. 1 a portion of a wheelrolling on its pitch-line under the tool T, the latter having the shapeof a truncated wedge. A series of these positions are shown in Fig. 2separated. The outline of the space, when formed as above described bythe tool T, consists of five separate portions, ab, 00, 0d, (1e, and ef.(See Fig. 3.) The curves ab and cf areinv olutes evolved from a circlesmaller than the pitclrcircle, whose diameter depends upon the angle ofthe wedge-shaped tool. They are those parts of the teeth which come inworking contact with the teeth of mating wheels. An inspection of Fig. 2will show that those parts of the space are produced by the flat sidesof the wedge-shaped tool T. The portions b0 and de are prolateinvolut-cs, and are commonly called clearance-curves,- as these parts ofthe teeth never come in contact with the heating wheel, but merely makeroonrfor a free passage of the points of the teeth of the mat ing wheel.These curves are produced by the corner-points of the tool T. Theportion ad is the bottom of the space, and is formed by the front edgeof the tool. In applying this principle to the formation of the teethofbevel- 9 wheels, in which the spaces'between the teeth have not auniform width, only one of the sides of each space can be cut at onetime, and the tool must be so narrow that it can pass through thenarrowest part of the space. Each side of the teeth must thus be formedby a separate evolution. At the same time the rolling of the bevel-wheelblank must be that of its pitch-cone rolling on a plane, and as thenatural motion of a cone rolling on a plane surface consists in, first,a motion of its axis tracing a conical surface-4. c, a motion resemblingthat of a conical e1nlulum-and, second, in a rotation on this axis amachine for the said purpose must embody these two movements in itsconstruction.

Having given a general outline of the principle on which my invention isbased, I now proceed to describe the machine for cutting the teeth ofbevel-wheels.

In Figs. t and 5, A is the bed or frame of the machine, and B thereciprocating slide or head of a shaping-machine carrying the tool T. Ois a plate, with circular grooves, carrying two uprights, I) I), and isshown detached in Figs. (3, '7, and S. It is held in position on themachine by means of the grooved ring E, which is securely screwed to thebed,and which permits the plate 0 to rotate on its geometrical axis Y Y.through the hand-wheel F and the pinion G, gearing into the toothed rimof the plate C. Between the two uprights D D of the plate 0 is held bybolts a block, H, (see Figs. 4-, 5, and 9,) forming the bearing for thearbor I. This bearing II can be sceuredto the plate (J at any desirableangle. The arbor I carries the blank K of the wheel to be cut on oneside of its bearing II. ()n the other side it carries the formencone )I,which is free to turn on it, and the lever L, which is firmly secured bymeans of a clamp-screw. Firmly fastened to the former-cone MI is theindex-plate N, on which there are two rows of holes, each row beingdivided in as many divisions as the bevelwhcel K is to have teeth.Bythepinl, which is carried by the lever L and enters into thedivision-holes ot'the index-plateN, the formercone )I can be coupled tothe arbor I. The former-cone M is made of an angle correspond ing withthe angle of the conical pitch of the bevel-wheel K, and the block H isso located between the uprights 1) I) that the axis Z Z of the arbor Iintersects the geometrical axis Y Y of the plate C- in the plane XX, towhich plane the former-cone )I must be tangential. The point 0 ofintersection is the geometrical center of the machine. Two bands, Q andQ, of steel or other suitable material, of each of which one end issecured to the frame of the machine, while the other is fastened to theformer-cone 3f, hold the latter confined, so that it can assume only arolling motion, but cannot slip on the plane X X when its axis is moved.The plane X X forms an angle with the line of motion of the tool T equalto that angle which is formed by the bottom surface of the spaces of thebevel-wheel K with its conical pitch.

The operation of the machine is as follows: The blank K of the wheel tobe cut is firmly This rotation is accomplished fastened to the arbor, sothat its apex coincides with the point 0, and the tool Tis so adjustedthat one of its front corners is directed in a straight line toward thecenter 0 of the machine. The plate Cis moved so far to one side that thetoolT will clear theblank K and the machine is set in motion. By a slowfeeding motion on the hand-wheel F the plate Cris slowly rotated on itsaxis FY. This motion causes the axis Z Z of the arbor I to trace aconical surface, andthe former-cone M is forced to assume a rollingmotion on the plane X X, slipping being prevented by the two bands Q andQ. The blank K will participate in this rolling motion, assumingsuccessively positions in relation to the tool '1 similar to thoseindicated in Fig. 2, and the tool will produce a space of which one sidehas the correct form for beVcLgeai-ing. IVhen the feeding has beencontinued so far that the tool has made its exit from the space, theplate (3 is moved back to its original position by the hand-wheel F, andthe pin 1 withdrawn from the index-plate X and entered into the adjoining hole after a partial rotation of the arbor I. The operation ofrolling the blank K is then repeated asbefore and continued until allteeth of the bevel-wheel K are finished to this stage.

Then the tool is readjusted so that the other corner-point moves in astraight line toward the center 0 of the machine, and the pin Pisadjusted to the second row of holes of the index-plate N. This secondrow of holes is so located in relation to the first row that the teethof the bevel-wheel will obtain the proper thickness. The operation abovedescribed is then repeated for the second side of the teeth and thebevel-wheel is completed.

If the machine is required to do a variety of work, it will bcneccssaryto make the angle adjustable, by which the plane X Xis inclined to theline of motion of the tool T.

I claim- 1. As an improvement in bevcl-gear-cutting machines, astraightedged, truncated, V- shaped tool, adapted to cut with itsstraight sides the curved working-faces of the teeth of the bevel-wheelthrough evolution, substantially as described.

2. Inbevel-gear-cutting machines, thearbor I, carrying the blank K, thebearing II of said arbor being secured in an inclined position to theplate 0, which is made to revolve on its geometrical axis Y Y, and byits revolution transmits to the center line of the arbor I a motiontracing a conical surface, substantially as described.

3. In bevel-gear-cuttin g machines,the former-cone 1f, fitted to theinclined arbor I, in combination with the bands Q. and Q, whereby saidconc describes a rolling motion when said arbor makes the aforesaidconical movement, substantially as described.

t. In bevel-gear-cutting machines, the combination, with the index-plateN, lever L, and pin 1, of the former-cone M. and the arbor I,

IIO

whereby said former-cone can be coupled to hearing H, arbor I,former-cone M, with bands the arbor I in various positions in order thatQ and Q, index-plate N, lever L, and pin P, the rolling motion of thecone may be trans substantiallyas and for the purpose described. IO

mitted to said arbor. 1 HUGO BILGRAM. 5 5. In bevel-gear-cuttingmachines, the com- I Witnesses:

bination of the reciprocating tool '1 and its i- GEO. L. PFOUTS,

holder B with the rotating plate 0, inclined 1 F RED. G. JAHN.

